A coating can be produced by spraying powdered polyolefin onto a substrate heated to a temperature that is higher than the melting temperature of the polyolefin. An alternative form of this process consists in immersing a heated substrate in a fluidized bed of polyolefin powder. This type of process is difficult to use when the substrates to be coated are of large size or when it is desired to coat only part of the substrate. Moreover, when it is the inner wall of a chemical reactor that it is desired to coat, access by the operator or the operator's intervention may not be possible. Furthermore, this type of process produces coatings that are not very adherent, especially because they are very thick and not very uniform in thickness.